ES2898611T3 - Common search space for machine type communications - Google Patents

Abstract

A method for wireless communications performed by a base station, BS, comprising: receiving (702) a physical random access channel, PRACH, signal from a first user equipment, UE, in a first narrowband region comprising of one to six resource blocks, RBs, within a wider uplink system bandwidth, UL; determining a first search space (1032, 1034) in which a random access response, RAR, message is transmitted based at least in part on the coverage enhancement level, CE, of the UE; and transmitting (704), in response to the PRACH signal, the RAR message in the first search space, which is in a second narrowband region comprising one to six RBs within a wider system bandwidth. downlink, DL, in at least a first subframe.

Description

DESCRIPTION

Common search space for machine type communications

Background

field of invention

Certain aspects of this disclosure relate generally to wireless communications and more specifically to configuration of the search space in systems using devices with limited communications resources, such as machine type communication (MTC) devices and enhanced or enhanced MTC devices. evolved (eMTC).

Description of Related Art

Wireless communication systems are widely implemented to provide various types of communication content, such as voice, data, etc. These systems may be multiple access systems capable of supporting communication with multiple users by sharing available system resources (eg, bandwidth and transmission power). Examples of such multiple access systems include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Third Generation Partnership Project (3GPP) of Long Term Evolution (LTE) that includes advanced LTE Systems and orthogonal frequency division multiple access (OFDMA) systems.

In general, a wireless multiple access communication system can simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations through transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. This communication link can be established through a single input single output, single input multiple output, or MIMO (multiple input multiple output) system.

A wireless communication network may include a number of base stations that can support communication for a number of wireless devices. Wireless devices may include user equipments (UEs). Some UEs may be considered machine type communication (MTC) UEs, which may include remote devices, which may communicate with a base station, another remote device, or some other entity. Machine Type Communications (MTC) may refer to communications involving at least one remote device at at least one end of the communication and may include forms of data communication which involve one or more entities that do not necessarily require human interaction. MTC UEs may include UEs that are capable of MTC communications with, for example, MTC servers and/or other MTC devices via Public Land Mobile Networks (PLMN).

LG Electronics: “Discussion on Common Control Messages for MTC UEs”; R1-152709 refers to multiplexing between UEs in normal coverage for both RAR and paging. Huawei et al: “RAR transmission for MTC UEs”; R1-151269 relates to frequency and time resource determination and RA-RNTI identification. US 2013/0083749 A1 relates to a method including a random access channel configuration for narrow bandwidth operations within a wider LTE system bandwidth. Huawei et al: “Discussion on PRACH coverage improvement and mechanism for determining the amount of needed coverage improvement”; R1-124054 refers to an analysis of the use of PRACH to indicate the level of coverage improvement and the resource multiplexing approach. US 2014/0071936 A1 relates to a method for encrypting allocated signals in predetermined radio resources. US 2014/0098761 A1 refers to a method to improve the coverage of a low cost MTC WTRU.

Summary

The invention is set forth in the appended set of claims.

Brief description of the drawings

In order that the manner in which the aforementioned features of the present disclosure may be understood in detail, a more particular description, briefly summarized above, may be given with reference to aspects, some of which are illustrated in the accompanying drawings. . It should be noted, however, that the attached drawings illustrate only certain typical aspects of this disclosure and, therefore, should not be considered limiting its scope, since the description may admit other equally effective aspects.

Figure 1 is a block diagram conceptually illustrating an exemplary wireless communications network, in accordance with certain aspects of the present disclosure.

Figure 2 is a block diagram conceptually illustrating an example of an evolved nodeB (eNB) in communication with user equipment (UE) in a wireless communications network, in accordance with certain aspects of the present disclosure.

Figure 3 is a block diagram conceptually illustrating an example frame structure for a particular radio access technology (RAT) for use in a wireless communications network, in accordance with certain aspects of the present disclosure.

Figure 4 illustrates example subframe formats for downlink with a normal cyclic prefix, in accordance with certain aspects of the present disclosure.

Figures 5A and 5B illustrate an example of coexistence of MTC within a broadband system, such as LTE, in accordance with certain aspects of the present disclosure.

Figure 6 illustrates an exemplary mapping of DL narrowband regions to UL narrowband regions, in accordance with certain aspects of the present disclosure.

Figure 7 illustrates an example operation for wireless communications that may be performed by a BS, in accordance with certain aspects of the present disclosure.

Figure 8 illustrates an example operation for wireless communications that a UE may perform, in accordance with certain aspects of the present disclosure.

Figure 9 illustrates example techniques for multiplexing MPDCCHs, in accordance with certain aspects of the present disclosure.

Figure 10 illustrates exemplary MPDCCH common search spaces, in accordance with certain aspects of the present disclosure.

Figure 11 illustrates an example operation for wireless communications that may be performed by a BS, in accordance with certain aspects of the present disclosure.

Figure 12 illustrates an example operation for wireless communications that a UE may perform, in accordance with certain aspects of the present disclosure.

Figure 13 illustrates an example operation for wireless communications that a BS may perform, in accordance with certain aspects of the present disclosure.

Figure 14 illustrates an example operation for wireless communications that a UE may perform, in accordance with certain aspects of the present disclosure.

Figure 15 illustrates exemplary transmission timelines of a BS and UE operating in accordance with aspects of the present disclosure.

Detailed description

Aspects of the present disclosure provide techniques and apparatus for enhanced paging messages and random access response (RAR) messages for devices with limited communication resources, such as low-cost (LC) machine-type communication (MTC) devices. , LC enhanced MTC (eMTC), etc. MTC and eMTC devices can receive MTC physical downlink control channel (MPDCCH) transmissions carrying paging messages and RAR messages. MTC and eMTC devices may attempt to decode MPDCCH candidates in time and frequency transmission resource search spaces. MPDCCHs may be transmitted in common paging spaces (CSS). Base stations may transmit MPDCCHs carrying selected CSS paging and RAR messages based at least in part on a receiving UE's coverage enhancement (CE) level and/or a subband used by a UE when transmitting a receiving UE. physical random access (PRACH). To improve the coverage of certain devices, such as MTC and eMTC devices, "bundling" can be used in which certain transmissions are sent as a packet of transmissions, for example, with the same information transmitted across multiple subframes.

Consequently, as will be described in more detail below, the techniques presented herein can allow cells to transmit and MTC devices to receive paging and RAR messages that are grouped together to achieve a CE of up to 15 dB. In addition, the techniques presented herein can allow cells to transmit and MTC devices to receive paging messages. and RAR in situations where a cell needs to transmit paging and RAR messages in one subframe, which is sometimes called a paging-RAR collision.

The techniques described in this document can be used for various wireless communication networks, such as Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency (FDMA), Orthogonal fDmA networks (OFDMA), Single Carrier FDMA Networks (SC-FDMa ), etc. The terms "network" and "system" are often used interchangeably. A CDMA network may implement radio technology such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Wideband CDMA (W-CDMA), Time Division Synchronous CDMA (TD-SCDMA), and other variants of CDMA. cdma2000 covers the IS-2000, IS-95 and IS-856 standards. A TDmA network may implement radio technology such as Global System for Mobile Communications (GSM). An OFDMA network can implement a radio technology such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM®, etc. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A), both frequency division duplex (FDD) and time division duplex (TDD), are new versions of UMTS which use E- UTRA, which uses OFDMA on the downlink and SC-FDMA on the uplink. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization called the “Third Generation Partnership Project” (3GPP). cdma2000 and UMB are described in documents from an organization called “Third Generation Partnership Project 2” (3GPP2). The techniques described herein can be used for the aforementioned wireless networks and radio technologies, as well as other wireless networks and radio technologies. For clarity, certain aspects of the techniques for LTE/LTE-A are described below, and LTE/LTE-A terminology is used throughout much of the description that follows. LTE and LTE-A are generally referred to as LTE.

Figure 1 illustrates an exemplary wireless communication network 100 with base stations (BSs) and user equipments (UEs), on which aspects of the present disclosure may be practiced.

For example, one or more paging enhancements may be supported for certain UEs (eg, LC MTC UEs, LC eMTC UEs, etc.) in the wireless communication network 100 . In accordance with the techniques presented herein, the BSs and LC UE(s) in the wireless communication network 100 may be able to determine, from the available system bandwidth supported by the wireless communication network 100, which narrowband region(s) the LC UE(s) should monitor for a packet paging message transmitted from the BSs in the wireless communication network 100 . Furthermore, in accordance with the techniques presented herein, the BSs and/or LC UE(s) in the wireless communication network 100 may be capable of determining and/or adapting the packet size for the paging message based on in one or more activators in the wireless communication network 100 .

The wireless communication network 100 may be an LTE network or some other wireless network. Wireless communication network 100 may include various evolved NodeBs (eNBs) 110 and other network entities. An eNB is an entity that communicates with user equipment (UEs) and can also be called a base station, Node B, access point (AP), etc. Each eNB can provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to a coverage area of an eNB and/or an eNB subsystem serving this coverage area, depending on the context in which the term is used.

An eNB can provide communication coverage for a macrocell, a picocell, a femtocell, and/or other cell types. A macro cell may cover a relatively large geographic area (eg, several kilometers in radius) and may allow unrestricted access by UEs subscribing to the service. A picocell may cover a relatively small geographic area and may allow unrestricted access by UEs subscribing to the service. A femtocell may cover a relatively small geographic area (eg, a home) and may allow restricted access by UEs that have association with the femtocell (eg, UEs in a closed subscriber group (CSG)). An eNB for a macrocell may be called a macro eNB. An eNB for a picocell can be called a pico eNB. An eNB for a femtocell may be called a femto eNB or a home eNB (HeNB). In the example shown in Figure 1, an eNB 110a can be a macro eNB for a macrocell 102a, an eNB 110b can be a pico eNB for a picocell 102b, and an eNB 110c can be a femto eNB for a femtocell 102c. . An eNB can support one or several (eg three) cells. The terms "eNB", "base station", and "cell" may be used interchangeably herein.

Wireless communication network 100 may also include relay stations. A relay station is an entity that can receive a data transmission from a previous station (for example, an eNB or a UE) and send a data transmission to a later station (for example, a UE or an eNB). . A relay station may also be a UE that can relay transmissions for other UEs. In the example shown in Figure 1, a relay (station) eNB 110d may communicate with the macro eNB 110a and a UE 120d in order to facilitate communication between the eNB 110a and the UE 120d. A relay station may also be called a relay eNB, relay base station, relay, etc.

Wireless communication network 100 may be a heterogeneous network including eNBs of different types, eg, macro eNBs, pico eNBs, femto eNBs, relay eNBs, and so on. These different types of eNBs may have different transmission power levels, different coverage areas, and a different impact on interference in the wireless communication network 100 . For example, macro eNBs can have a high transmit power level (for example, 5 to 40 W) while pico eNBs, femto eNBs, and relay eNBs can have lower transmit power levels ( for example, 0.1 to 2 W).

A network controller 130 may be coupled to a set of eNBs and may provide coordination and control for these eNBs. The network controller 130 may communicate with the eNBs via backhaul. eNBs can also communicate with each other, for example directly or indirectly via wireless or wired backhaul.

The UEs 120 (eg, 120a, 120b, 120c) may be dispersed throughout the wireless communication network 100, and each UE may be stationary or mobile. A UE may also be called an access terminal, terminal, mobile station (MS), subscriber unit, station (STA), etc. A UE can be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a smartphone, a small laptop, a smart book, a smart computer, navigation devices, gaming devices, cameras, a vehicular device, a drone, a robot/robotic device, a wearable device (e.g., watch smart wear, smart bracelet, smart ring, smart bracelet, smart glasses, virtual reality glasses), a medical device, a health device, etc. MTC UEs include devices such as sensors, gauges, monitors, location tags, drones, trackers, robots/robotic devices, etc. UEs (eg MTC devices) can be implemented as Internet of Everything (IoT) or Internet of Things (IoT) devices (eg narrowband IoT (NB-IoT)).

One or more UEs 120 in the wireless communication network 100 (eg, an LTE network) may also be low data rate, low cost (LC) devices, for example, such as LC MTC UEs, LC eMTC UEs, etc. LC UEs may coexist with legacy and/or advanced UEs in the LTE network and may have one or more capabilities that are limited compared to the other UEs (eg, non-LC UEs) in the wireless network. For example, compared to legacy and/or advanced UEs in the LTE network, LC UEs may operate with one or more of the following: a reduction in maximum bandwidth (relative to legacy UEs), a single receive radio frequency (RF) chain, peak rate reduction, transmit power reduction, rank 1 transmit, half-duplex operation, etc. As used herein, devices with limited communication resources, such as MTC devices, eMTC devices, etc. they are generally referred to as LC UEs. Similarly, legacy devices, such as legacy and/or advanced UEs (eg, in LTE) are generally referred to as non-LC UEs.

Figure 2 is a block diagram of a BS/eNB 110 and UE 120 layout, which may be one of the BS/eNBs 110 and one of the UEs 120, respectively, in Figure 1. BS 110 may be equipped with antennas T 234a to 234t, and UE 120 can be equipped with antennas R 252a to 252r, where in general T > 1 and R > 1.

In BS 110, a transmission processor 220 may receive data from a data source 212 for one or more UEs, select one or more modulation and coding schemes (MCSs) for each UE based on channel quality indicators (CQIs) received from the UE, process (eg, encode and modulate) the data for each UE based on the selected MCS(s) for the UE, and provide data symbols for all UEs. Streaming processor 220 may also process system information (eg, for semi-static resource partitioning information (SRPI), etc.) and control information (eg, CQI requests, grants, upper layer signaling, etc. ) and provide general symbols and control symbols. Processor 220 may also generate reference symbols for reference signals (eg, common reference signal (CRS)) and timing signals (eg, primary timing signal (PSS) and secondary timing signal (SSS). )). A multiple input multiple output (MIMO) transmit (TX) processor 230 may perform spatial processing (eg, precoding) on the data symbols, control symbols, general symbols, and/or reference symbols. , if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each MOD 232 may process a respective output symbol stream (eg, for OFDM, etc.) to obtain an output sample stream. Each MOD 232 may further process (eg, convert to analog, amplify, filter, and decrease) the output sample stream to obtain a downlink signal. Downlink signals T from modulators 232a through 232t may be transmitted via T antennas 234a through 234t, respectively.

At UE 120, antennas 252a through 252r may receive downlink signals from BS 110 and/or other BSs and may provide received signals to demodulators (DEMOD) 254a through 254r, respectively. Each DEMOD 254 can condition (eg, filter, amplify, convert, and digitize) its received signal to obtain input samples. Each DEMOD 254 may further process the input samples (eg, for OFDM, etc.) to obtain the received symbols. A MIMO detector 256 may obtain the received symbols from all R demodulators 254a to 254r, perform MIMO detection on the received symbols, if applicable, and provide the detected symbols. A receiver processor 258 may process (eg, demodulate and decode) the detected symbols, provide decoded data for the UE 120 to a data collector 260, and provide information decoded control and system information to a controller/processor 280. A channel processor may determine received reference signal strength (RSRP), received signal strength indicator (RSSI), received reference signal quality (RSRQ), CQI, etc.

On the uplink, at UE 120, a transmission processor 264 may receive and process data from a source 262 of data and control information (eg, for reports comprising RSRP, RSSI, RSRQ, CQI, etc.) from the controller/processor 280. Processor 264 may also generate reference symbols for one or more reference signals. Symbols from transmit processor 264 may be pre-encoded by a TX MIMO processor 266 if applicable, further processed by MODs 254a through 254r (eg, for SC-FDM, OFDM, etc.), and transmitted to BS 110. At BS 110 , uplink signals from UE 120 and other UEs may be received by antennas 234, processed by DEMODs 232, detected by MIMO detector 236 if applicable, and further processed by receiver processor 238 to obtain decoded data and signal information. sent by UE 120. Processor 238 may provide the decoded data to a data collector 239 and the decoded control information to controller/processor 240. BS 110 may include communication unit 244 and communicate with network controller 130 via communication unit 244. Network controller 130 may include communication unit 294, controller/processor 290, and memory 292.

Controller/processors 240 and 280 may direct the operation at BS 110 and UE 120, respectively. For example, controller/processor 240 and/or other processors and modules in BS 110 may perform or direct operations that are illustrated in Figures 7, 11, 13 and/or other processes for the techniques described herein. Similarly, controller/processor 280 and/or other processors and modules in UE 120 may perform or direct operations that are illustrated in Figures 8, 12, 14 and/or processes for the techniques described herein. Memories 242 and 282 can store data and program code for BS 110 and UE 120, respectively. A scheduler 246 may schedule UEs for downlink and/or uplink data transmission.

Figure 3 shows an example frame structure 300 for FDD in LTE. The transmission timeline for each downlink and uplink can be divided into units of radio frames. Each radio frame may have a predetermined duration (eg, 10 milliseconds (ms)) and may be divided into 10 subframes with indices from 0 to 9. Each subframe may include two slots. Thus, each radio frame can include 20 slots with indices 0 to 19. Each slot can include L symbol periods, for example seven symbol periods for a normal cyclic prefix (as shown in Figure 3) or six symbol periods for an extended cyclic prefix. The 2L symbol periods in each subframe can be assigned indices from 0 to 2L-1.

In LTE, an eNB can transmit a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) on the downlink in the center of 1.08 MHz of the system bandwidth for each cell supported by the eNB. PSS and SSS can be transmitted in symbol periods 6 and 5, respectively, in subframes 0 and 5 of each radio frame with the normal cyclic prefix, as shown in Figure 3. UEs can use PSS and SSS for searching and acquiring cells. The eNB can transmit a cell specific reference signal (CRS) over the system bandwidth for each cell supported by the eNB. The CRS may be transmitted at certain symbol periods of each subframe and may be used by UEs to perform channel estimation, channel quality measurement, and/or other functions. The eNB can also transmit a physical broadcast channel (PBCH) in symbol periods 0 to 3 in interval 1 of certain radio frames. The PBCH may contain system information. The eNB may transmit other system information, such as system information blocks (SIBs) on a physical downlink shared channel (PDSCH) in certain subframes. The eNB may transmit control data/information on a physical downlink control channel (PDCCH) in the first B symbol periods of a subframe, where B may be configurable for each subframe. The eNB may transmit traffic data and/or other data on the PDSCH in the remaining symbol periods of each subframe.

The PSS, SSS, CRS, and PBCH in LTE are described in 3GPP TS 36.211, entitled “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation”, which is publicly available.

Figure 4 shows two example subframe formats 410 and 420 for the downlink with a normal cyclic prefix. The time rate resources available for the downlink may be divided into resource blocks. Each resource block may cover 12 subcarriers in one slot and may include a number of resource elements. Each resource element can cover one subcarrier in a symbol period and can be used to send a modulation symbol, which can be a real or complex value.

Subframe format 410 can be used for an eNB equipped with two antennas. A CRS can be transmitted from antennas 0 and 1 at symbol periods 0, 4, 7, and 11. A reference signal is a signal that is known a priori by a transmitter and a receiver and can also be called a pilot. A CRS is a reference signal that is specific to a cell, eg generated based on a cell identity (ID). In Figure 4, for a given resource element labeled Ra, a modulation symbol may be transmitted on that resource element from antenna a, and no modulation symbols may be transmitted on that resource element from antenna a. from other antennas. The 420 subframe format can be used for an eNB equipped with four antennas. a CRS can be transmitted from antennas 0 and 1 in periods 0, 4, 7, and 11 and from antennas 2 and 3 in symbol periods 1 and 8. For both 410 and 420 subframe formats, a CRS can be transmitted on uniformly spaced subcarriers, which can be determined based on the cell ID. Different eNBs can transmit their CRSs on the same or different subcarriers, depending on their cell IDs. For both subframe formats 410 and 420, resource elements not used for the CRS may be used to transmit data (eg, traffic data, control data, and/or other data).

An interleaved structure can be used for each of the downlink and uplink for FDD in LTE. For example, interleaved Qs can be defined with indices from 0 to Q-1, where Q can be equal to 4, 6, 8, 10, or some other value. Each interlace may include subframes that are separated by Q frames. In particular, interleaving q may include subframes q, q+Q, q+2Q, etc., where qe {o, ..., Q -1}.

The wireless network can support Hybrid Automatic Retransmission Request (HARQ) for both downlink and uplink data transmission. For HARQ, a transmitter (eg, an eNB 110) may send one or more transmissions of a packet until the packet is successfully decoded by a receiver (eg, a UE 120) or some other termination condition is encountered. For synchronous HARQ, all transmissions of the packet may be sent in single interleaved subframes. For asynchronous HARQ, each packet transmission can be sent in any subframe.

A UE may be located within the coverage of multiple eNBs. One of these eNBs can be selected to serve the UE. The serving eNB can be selected based on various criteria, such as received signal strength, received signal quality, path loss, etc. The quality of the received signal can be quantified by a signal-to-interference plus noise ratio (SINR), or a reference signal received quality (RSRQ), or some other metric. The UE may operate in a dominant interference scenario in which the UE may observe high interference from one or more interfering eNBs.

As mentioned above, one or more UEs in the wireless communication network (eg, wireless communication network 100) may be devices that have limited communication resources, such as LC UEs, compared to other (non-LC) devices. in the wireless communication network.

In some systems, for example in LTE Rel-13 and other versions, the LC UE may be limited to a particular narrowband allocation (for example, of no more than one resource block (RB) or no more than six RBs). ) within the available bandwidth of the system. However, the LC UE may retune (e.g. operate and/or camp) to different narrowband regions within the available system bandwidth of the LTE system, e.g. in order to coexist within the LTE system. .

As another example of coexistence within the LTE system, LC UEs may receive (with repetition) a Legacy Physical Transmission Channel (PBCH) (i.e. the LTE Physical Channel which generally carries parameters that may be used for initial access to cell) and support one or more legacy Physical Random Access Channel (PRACH) formats. For example, the LC UE may receive the legacy PBCH with one or more additional repetitions of the PBCH in multiple subframes. As another example, the LC UE may be able to transmit one or more PRACH repetitions (eg, with one or more supported PRACH formats) to an eNB in the LTE system. The PRACH can be used to identify the UE LC. In addition, the eNB can configure the number of repeated PRACH attempts.

The LC UE may also be a link budget limited device and may operate in different modes of operation (eg, involving different numbers of repeated messages transmitted to or from the LC UE) based on its link budget limitation. For example, in some cases, the LC UE may operate in a normal coverage mode in which there is little or no repetition (for example, the amount of repetition required for the UE to successfully receive and/or transmit a message may be low or repetition may not even be necessary). Alternatively, in some cases, the LC UE may operate in a coverage enhancement (CE) mode in which there may be large amounts of repetition. For example, for a 328-bit payload, an LC UE in CE mode may need 150 or more payload repetitions to successfully receive the payload.

In some cases, eg also for LTE Rel-13, the LC UE may have limited capabilities with respect to its reception of broadcast and unicast transmissions. For example, the maximum transport block size (TB) for a broadcast transmission received by the LC UE may be limited to 1000 bits. Also, in some cases, the LC UE may not be able to receive more than one unicast TB in a subframe. In some cases (eg, for both CE and normal mode described above), the LC UE may not be able to receive more than one broadcast TB in a subframe. Furthermore, in some cases, the LC UE may not be able to receive both a unicast TB and a transmit TB in a subframe.

For MTC, LC UEs coexisting in the LTE system may also support new messages for certain procedures, such as paging, random access procedure, etc. (for example, unlike the conventional messages used in LTE for these procedures). In other words, these new messages for paging, random access procedure, etc. they may be separate from messages used for similar procedures associated with non-LC UEs. For example, compared to messages from conventional paging used in LTE, LC UEs may monitor and/or receive paging messages that non-LC UEs may not be able to monitor and/or receive. Similarly, compared to conventional random access response (RAR) messages used in a conventional random access method, LC UEs can receive RAR messages that non-LC UEs cannot receive either. New paging and RAR messages associated with LC UEs may also be repeated one or more times (eg, "bundled"). Also, different numbers of repetitions (eg, different packet sizes) can be supported for new messages.

As mentioned above, the operation of MTC and/or eMTC may be supported in the wireless communication network (for example, in coexistence with LTE or some other RAT). Figures 5A and 5B, for example, illustrate an example of how LC UEs in MTC operation can coexist within a broadband system, such as LTE.

As illustrated in the example frame structure of Figure 5A, subframes 510 associated with MTC and/or eMTC operation may be time division multiplexed (TDM) with regular subframes 520 associated with LTE (or some other RAT). ).

Additionally or alternatively, as illustrated in the example frame structure of Figure 5B, one or more narrowband regions 560, 562 used by LC UEs in MTC are frequency division multiplexed within the widest bandwidth 550 supported. by LTE. Various narrowband regions, with each narrowband region spanning a bandwidth of no more than a total of 6 RBs, are supported for MTC and/or eMTC operation.

In some cases, each MTC operating LC UE may operate within a narrow-band region (eg, at 1.4 MHz or 6 RBs) at the same time. However, LC UEs in MTC operation, at any given time, may retune to other narrowband regions in the wider system bandwidth. In some examples, the same narrowband region may serve multiple LC UEs. In other examples, multiple LC UEs may be served by different narrowband regions (eg, with each narrowband region spanning 6 RBs). In yet other examples, the different combinations of LC UEs may be served by one or more of the same narrowband regions and/or one or more different narrowband regions.

The LC UEs may operate (eg, monitor/receive/transmit) within the narrowband regions for a number of different operations. For example, as shown in Figure 5B, a first narrowband region 560 (eg, encompassing no more than 6 RBs of the wideband data) of a subframe 552 may be monitored by one or more LC UEs for a PSS, SSS, PBCH, MTC signaling or paging transmission from a BS in the wireless communication network. As also shown in Figure 5B, LC UEs may use a second narrowband region 562 (eg, also encompassing no more than 6 RBs of the wideband data) of a subframe 554 to transmit a RACH or data. previously configured in the signaling received from a BS. In some cases, the second narrowband region may be used by the same LC UEs that used the first narrowband region (for example, the LC UEs may have retuned to the second narrowband region to transmit after the monitoring in the first narrowband region). In some cases (although not shown), the second narrowband region may be used by different LC UEs than the LC UEs that used the first narrowband region.

Although the examples described herein assume a narrow band of 6 RBs, those skilled in the art will recognize that the techniques presented herein can also be applied to different sizes of narrow band regions (e.g., 1 RB, supported). by NB-IoT).

As mentioned above, in certain systems, eg, such as LTE Rel-12, narrowband operation for MTC (eg, eMTC) may be supported. A cell that supports narrowband operation for MTC may have different system bandwidths for downlink (DL) and uplink (UL) operations. A cell having different DL and UL system bandwidths (SBs) may organize DL system bandwidth into narrowband regions in a different way than the way used to organize UL system bandwidth into narrowband regions. Narrow band. Accordingly, aspects of the present disclosure provide techniques for organizing a DL system bandwidth and a UL system bandwidth into narrowband regions.

A cell that supports narrowband operation for MTC and legacy UEs may receive legacy PUCCH transmissions from the legacy UEs. Legacy PUCCH transmissions can be transmitted on one or both edges of the bandwidth of a single cell UL system. Accordingly, aspects of the present disclosure provide techniques for reserving transmission resources that are included in a UL narrowband region for use by legacy PUCCH transmissions. Similar reservations can also be applied to a DL narrowband region for use by other signals or legacy DL channels.

A cell that supports narrowband operations for MTC may also support the transmission of sounding reference signals (SRS). The current defined minimum bandwidth for SRS transmission is four RBs. However, as mentioned above, the bandwidth of the narrow band regions is six RBs.

The fact that six RBs are not divisible by four RBs presents challenges in managing SRS transmissions using four RBs in narrowband operations based on six RBs. Accordingly, aspects of the present disclosure provide techniques for allocating transmission resources for SRS transmission in a cell that supports narrowband operations (eg, for MTC).

A cell operating with FDD may have a DL system bandwidth that is a different size than the cell's UL system bandwidth. For example, a cell can perform DL operations on a system bandwidth of ten MHz and UL operations on a system bandwidth of five MHz. To allow MTC operations and MTC UEs, the cell can organize the bandwidth of the DL system and UL system bandwidth in narrowband regions, or narrowband regions. An eNB or other Bs controlling the cell may assign a DL narrowband region to an MTC UE for the MTC UE to monitor signals from the eNB. Similarly, the eNB (or other BS) may allocate a UL narrowband region to the MTC UE for the MTC to use when transmitting UL signals. In the example, the cell can organize the DL system bandwidth into eight DL narrowband regions while organizing the UL system bandwidth into four UL narrowband regions.

When a BS (for example, an eNB or a cell) supports MTC UE with the DL system bandwidth and the UL system bandwidth of the cell organized in narrow-band regions, the BS can establish a mapping between the DL narrowband regions and UL narrowband regions, such that the assignment of a DL narrowband region to an MTC UE implies an assignment of a UL narrowband region to that MTC UE. Having a mapping allows the BS to simplify resource scheduling in the cell, eg the BS can expect ACK/nAKs for transmissions in a narrowband region DL to a MTC UE in the corresponding narrowband region UL. Also, an MTC UE monitors DL transmissions in the assigned DL narrowband region for the MTC UE and responds with transmissions in the corresponding UL narrowband region.

In accordance with aspects of the present disclosure, a technique for mapping narrowband UL and DL regions via a BS is provided. A BS can determine a minimum size of the UL system bandwidth and the DL system bandwidth supported by the BS, determine a number of narrowband regions that can be arranged in the given size, and then arrange both the width bandwidth of the DL system as the bandwidth of the UL system in that number of narrowband regions. The BS can then map each DL narrowband region to a UL narrowband region. For example, a cell can perform DL operations on a system bandwidth of ten MHz and UL operations on a system bandwidth of five MHz. In the example, the BS can determine that the minimum size of the bandwidth of the UL system and the DL system bandwidth is five MHz, and then determine that the BS can organize four narrowband regions in a five MHz system bandwidth. Still in the example, the BS can organize four narrowband regions DL narrowband regions into the DL system bandwidth and four UL narrowband regions into the UL system bandwidth, and mapping each DL narrowband region to a UL narrowband region.

Figure 6 illustrates an exemplary mapping 600 of DL narrowband regions to UL narrowband regions, as described above. Such mapping can be employed by eNB 110a in Figure 1. While Figure 6 shows the DL system bandwidth 610 and the UL system bandwidth 650 apparently in the same frequency ranges, the bandwidth DL system bandwidth and UL system bandwidth are in different frequency ranges in a cell using FDD. The DL system bandwidth 610 is ten MHz or fifty RBs wide, and the UL system bandwidth 650 is five MHz or twenty-five RBs wide. A BS that supports MTC UEs while operating DL system bandwidth 610 and UL system bandwidth 650 may determine that UL system bandwidth 650 is less than DL system bandwidth 610 (5 MHz size of UL system bandwidth 650 is the minimum size of UL system bandwidth 650 and DL system bandwidth 610). The BS can then determine that the BS can organize four narrowband regions 652, 654, 656, and 658 from the bandwidth 650 of the UL system. The BS can then determine to arrange four narrowband regions from the DL system bandwidth, and arrange narrowband DL regions 612, 614, 616, and 618 from the DL system bandwidth. The BS can then map DL narrowband region 612 to UL narrowband region 652, DL narrowband region 614 to UL narrowband region 654, DL narrowband region 616 to UL narrowband region 656, and DL narrowband region 618 with UL narrowband region 658.

As mentioned above, LC MTC UEs were introduced in LTE Rel-12. Additional enhancements may be made to LTE version 13 (Rel-13) to support eMTC operations. For example, MTC UEs may operate (eg, monitor, transmit, and receive) in a narrow 1.4 MHz band region or six RBs within wider system bandwidths (eg, 1.4 MHz, 3 MHz, 5MHz, 10MHz, 15MHz, 20MHz). As a second example, base stations and MTC UEs can support coverage enhancements (CE) of up to 15 dB by some techniques, eg, bundling. Coverage enhancement can also be called coverage extension and range extension.

Other enhancements that can be made to LTE Rel-13 may include base stations transmitting paging signals on MTC Physical Downlink Control Channels (MPDCCHs) in a narrow band in order to locate MTC UEs. An MPDCCH may carry paging signals for multiple MTC UEs and downlink control information (DCI) to one or more other MTC UEs. MPDCCH may be similar to PDCCH/EPDCCH as described above. Demodulation based on the demodulation reference signal (DM-RS) may be supported when MPDCCH is used. That is, a BS transmitting an MPDCCH may transmit DM-RS with the MPDCCH. A UE receiving the MPDCCH and the DM-RS may demodulate the MPDCCH based on the DM-RS.

Enhancements that can be made to LTE Rel-13 can also include BSs that transmit random access response (RAR) signals on an MPDCCH in a narrow band to respond to physical random access channel (PRACH) signals from MTC UEs. A BS may send a single RAR message on a DCI on an MPDCCH or multiple RAR messages (eg, to reply to multiple UEs) on an MPDCCH without a DCI.

A UE that has an active receiver (eg, the receiver is not turned off) typically monitors PDCCHs (eg, EPDCCH, MPDCCH) in one or more search spaces. The UE typically monitors at least one common search space and can be configured to monitor a specific UE search space. A search space includes a set of groups of contiguous control channel elements (CCE). The UE uses an identifier (eg, a Radio Network Temporary Identifier (RNTI)) of the UE to determine if any of the groups in the search space contain a PDCCH addressed to the UE. Monitoring of PDCCHs is described in more detail in 3GPP TS 36.213 “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures”, which is publicly available.

Figure 7 illustrates exemplary operation 700 for wireless communications that may be performed by a BS (eg, eNodeB 110a in Figure 1), in accordance with previously disclosed aspects of the present disclosure. Operation 700 may be performed by a BS to support MTC UEs, and may use one of the example techniques illustrated in Figures 9-10 below.

Operation 700 begins at block 702, where the BS receives a physical random access channel (PRACH) signal from a first user equipment (UE) in a first narrowband region within a wider bandwidth of the system. Operation 700 continues at block 704, where the BS transmits, in response to the PRACH signal, a random access response (RAR) message in a first search space in a second narrowband region in at least a first subplot.

In accordance with aspects of the present disclosure, a BS (eg, the BS mentioned in Figure 7) may transmit a paging signal in a second paging space in a third narrowband region. That is, a BS may transmit paging signals in narrowband regions other than the narrowband regions used for PRACH and RAR messages.

In accordance with aspects of the present disclosure, a BS (eg, the BS mentioned in Figure 7) can identify a third search space in a fourth narrowband region to transmit RAR messages to a second UE with an enhancement level of different coverage (CE) than the first UE. The BS may also transmit information about the first search space and a first CE level for the first search space in a system information block (SIB) and transmit information about the third search space and a second CE level for the third search space in at least one of the SIBs or another SIB. That is, a BS may transmit information about search spaces and CE levels in one or more SIBs.

In accordance with aspects of the present disclosure, a BS (eg, the BS mentioned in Figure 7) may transmit information regarding the first search space in a SIB. For example, a BS that does not differentiate between CE levels may broadcast information about a search space in a SIB.

In accordance with aspects of the present disclosure, a BS (eg, the BS mentioned in Figure 7) can determine a RAR response window, a set of physical downlink control channel (MPDCCH) starting point subframes. machine type communications (MTC), a number of RAR offset subframes, and a packet size for each of a plurality of coverage enhancement (CE) levels. That is, a BS may use different RAR response windows, MPDCCH start point subframes, RAR offset numbers, and packet sizes for different CE levels, and the BS may determine those various RAR response windows, MPDCCH start point subframes, MPDCCH start numbers, RAR offset numbers, and packet sizes for the different CE levels.

In accordance with aspects of the present disclosure, a BS (for example, the BS mentioned in Figure 7) may determine a paging radio frequency, a paging time, a paging packet size, and a set of paging packets. of monitoring candidates based on at least one level of maximum coverage improvement (CE) admitted by the BS.

In accordance with aspects of the present disclosure, a BS (eg, the BS mentioned in Figure 7) may refrain from transmitting a dedicated channel to the first UE for at least a second subframe and transmit at least one system information change ( SI) or earthquake and tsunami warning system (ETWS) signal on a transmission channel of the widest bandwidth of the system during at least the second subframe.

Figure 8 illustrates example operation 800 for wireless communications that a UE (eg, UE 120a in Figure 1) may perform, in accordance with aspects of the present disclosure. Operation 800 may be performed by an MTC UE, for example, and may use one of the illustrative techniques illustrated in Figures 9-10 below. Operation 800 can be considered complementary to operation 700 in Figure 7 described above.

Operation 800 begins at block 802, where the UE transmits a physical random access channel (PRACH) signal to a base station (BS) in a first narrowband region within a wider system bandwidth. Operation 800 continues at block 804, where the UE receives, in response to the PRACH signal, a random access response (RAR) message in a first search space in a second narrowband region in at least a first subplot.

In accordance with aspects of the present disclosure, an MTC UE may be configured with a common MPDCCH search space (eg, the first search space mentioned in block 804 above) within a narrowband region of larger bandwidth. system wide. A BS serving MTC UEs may be configured to transmit MPDCCHs carrying paging signals and RAR messages on a common MPDCCH search space (eg, the first search space mentioned in block 704 above) within a narrowband region of wider system bandwidth.

In accordance with aspects of the present disclosure, a BS may transmit paging signals and RAR messages (eg, the RAR message mentioned in block 804 above) on MPDCCHs within a common MPDCCH paging space, in accordance with aspects of the this disclosure. A BS transmitting MPDCCHs within a common MPDCCH paging space may multiplex paging and RAR messages within the MPDCCHs.

In accordance with aspects of the present disclosure, a UE (eg, the UE mentioned in Figure 8) can identify a third search space in a fourth narrowband region to receive RAR messages based at least in part on a level CE from the UE, receive information about the first search space and a first CE level for the first search space in a system information block (SIB), and receive information about the third search space and a second CE level for the third search space in at least one of the SIBs or another SIB.

In accordance with aspects of the present disclosure, a UE (eg, the UE mentioned in Figure 8) can determine a RAR response window, a set of physical downlink control channel (MPDCCH) start point subframes. machine type communications (MTC), a number of RAR offset subframes, and a packet size for each of a plurality of coverage enhancement (CE) levels.

In accordance with aspects of the present disclosure, a UE (eg, the UE mentioned in Figure 8 ) may determine a radio frequency for paging, a time for paging, a packet size for paging, and a set of monitoring candidates based on at least one level of maximum coverage improvement (CE) admitted by the BS. The UE may also receive information about the maximum level of CE supported by the BS (eg, in a SIB transmitted by the BS).

In accordance with aspects of the present disclosure, a UE (eg, the UE mentioned in Figure 8) may receive at least one system information (SI) or earthquake and tsunami warning system (ETWS) change signal. in the second narrowband region.

In accordance with aspects of the present disclosure, a UE (eg, the UE mentioned in Figure 8) may receive at least one SI change or ETWS signal on a system's widest-bandwidth broadcast channel for at least a second subframe.

Figure 9 illustrates example techniques 910, 920, and 930 for multiplexing MPDCCHs carrying paging signals with MPDCCHs carrying RAR messages. In the exemplary technique 910, an MPDCCH 912 carrying a RAR message is frequency division multiplexed with an MPDCCH 914 carrying a paging signal. While the example technique shows the MPDCCHs grouped over K subframes (SF), the disclosure is not so limited and the MPDCCHs can be multiplexed into a single subframe. In exemplary technique 920, an MPDCCH 922 carrying a RAR message is time division multiplexed with an MPDCCH 924 carrying a paging signal. The technique shows each MPDCCH grouped over K subframes (SF), but the disclosure is not so limited and each MPDCCH can be transmitted in a single subframe. In the exemplary technique 930, an MPDCCH 932 carrying a RAR message is time division multiplexed with an MPDCCH 934 that carries a paging signal, but each MPDCCH is carried in a non-continuous packet 936, 938. That is, each MPDCCH is grouped into a plurality (eg, 2, 4, 8) of subframes, but each of the packets includes subframes that are not all consecutive.

When a BS locates a UE operating at a coverage enhancement (CE) level of more than 0 dB (eg, 3 dB, 15 dB), the BS may transmit a plurality or a packet of MPDCCHs carrying paging signals. in a plurality of subframes (eg, the packets illustrated in techniques 910, 920, and 930 in Figure 9 above) to the UE. The subframes can be continuous or discontinuous. That is, the BS may transmit MPDCCH in consecutive subframes, in groups of consecutive subframes with subframes between the groups, or in non-consecutive subframes. The paged UE may receive the MPDCCHs in the subframe packet, combine the paging signals, and decode the combination. Combining the MPDCCHs can increase the probability that the UE will successfully decode the MPDCCH and detect the paging signal.

A BS configured to support UEs with a CE level greater than 0 dB may signal, for example, in a system information block (SIB) or through radio resource control, information about a packet technique(s) (e.g. eg techniques 910, 920, and/or 930 in Figure 9 above) used by the BS when paging UEs. Such information may include, for example, an initial subframe of a paging occasion and a repeat pattern for the paging occasion. A UE supported by the BS can receive the information and determine which subframes contain MPDCCHs to combine when trying to decode an MPDCCH. A UE may use the information regarding the grouping technique(s) to determine the subframes containing MPDCCHs and combine the received signals into the subframes before attempting to decode the MPDCCH.

A UE that receives a time division multiplexed MPDCCH using non-continuous packets (eg, as illustrated in example technique 930 in Figure 9 above) can correctly decode an MPDCCH without waiting to receive the entire packet. This can happen in situations where a transmitting BS is configured to support a CE level higher than the CE level below which the receiving UE is operating. For example, a BS supporting a CE level of 15 dB may group each MPDCCH into ten subframes. In the example, a receiving UE that is in good signal condition and operating under a CE level of 0 dB can decode an MPDCCH after receiving a first subframe of the group of ten subframes.

Figure 10 illustrates example techniques 1010, 1020, and 1030 for configuring the MPDCCH common search space for MPDCCHs carrying paging signals and one or more MPDCCH common search spaces for MPDCCHs carrying RAR messages, in accordance with aspects of the present disclosure described above. In the exemplary technique 1010, a common MPDCCH paging space 1012 for MPDCCHs carrying RAR messages is configured in a first narrowband region and a common MPDCCH paging space 1014 for MPDCCHs carrying paging signals is configured in a second region. narrow band.

In the exemplary technique 1020, a first MPDCCH common search space 1022 for MPDCCHs carrying RAR messages is configured in a first narrowband region, a second MPDCCH common search space 1024 for MPDCCHs carrying RAR messages is configured in a second narrowband region. narrowband region, and a common MPDCCH paging space 1026 for MPDCCHs carrying paging signals is configured in a third narrowband region. The first MPDCCH common paging space 1022 for MPDCCHs carrying RAR messages is used to respond to packet size #1 PRACH signals, while the second MPDCCH common paging space 1024 for MPDCCHs carrying RAR messages is used to respond to PRACH signals of packet size #2. The technique shows two MPDCCH common search spaces for MPDCCHs carrying RAR messages, but the disclosure is not so limited and can be used with more MPDCCH common search spaces.

In the exemplary technique 1030, a first MPDCCH common search space 1032 for MPDCCHs carrying RAR messages is configured in a first narrowband region, a second MPDCCH common search space 1034 for MPDCCHs carrying RAR messages is configured in a second narrowband region. narrowband region, and a common MPDCCH paging space 1036 for MPDCCHs carrying paging signals is configured in a third narrowband region, similar to example technique 1020. The first MPDCCH common paging space 1032 for MPDCCHs carrying RAR messages is used to respond to PRACH signals received in narrowband region or subband #1, while the second MPDCCH common paging space 1034 for MPDCCHs carrying RAR messages RAR is used to respond to PRACH signals received in the narrowband region or subband #2. The technique shows two MPDCCH common search spaces for MPDCCHs carrying RAR messages, but the disclosure is not so limited and can be used with more MPDCCH common search spaces.

In accordance with aspects of the present disclosure, a BS serving MTC UEs may be configured to transmit MPDCCHs carrying paging signals on a first MPDCCH common search space and MPDCCHs carrying RAR messages on a second MPDCCH common search space on the first MPDCCH. and second narrowband regions of wider system bandwidth (eg, as in the exemplary technique 1010 in Figure 10 above).

A BS may be configured with a plurality of MPDCCH common search spaces for MPDCCHs carrying RAR messages. The BS may determine which MPDCCH common search space to use to transmit a RAR message based on the PRACH signal to which the RAR message responds (eg, as in technique 1020 in Figure 10 above). The BS may determine to transmit a RAR message on a first MPDCCH common search space if the BS received a PRACH signal grouped into x (eg two) or fewer subframes (corresponding to a CE level of i less for the transmitting UE). , and the BS may determine to transmit the RAR message in a second MPDCCH common search space if the BS received a PRACH signal grouped into x+1 (for example, three) or more subframes (corresponding to a CE level greater than y for the transmitting UE). A BS configured with more than two MPDCCH common search spaces to carry RAR messages may be configured to use each MPDCCH common search space to respond to PRACH signals in different PRACH signal packet size ranges.

Additionally or alternatively, a BS configured with a plurality of MPDCCH common search spaces to carry RAR messages may determine which MPDCCH common search space to use to transmit a RAR message based on a subband used to transmit the PRACH signal to which the RAR responds. RAR the message (eg, as in technique 1030 in Figure 10 above). The BS may determine to transmit a RAR message on a first common paging space MPDCCH if the BS received a PRACH signal in a first narrowband region or subband, and the BS may determine to transmit the RAR message on a second common paging space MPDCCH if the BS received a PRACH signal in a second narrowband region or sub-band. A BS configured with more than two MPDCCH common search spaces to carry RAR messages may be configured to use each MPDCCH common search space to respond to PRACH signals in a different narrowband region.

In accordance with aspects of the present disclosure, a BS transmits information regarding which MPDCCH common search space the BS will use to transmit MPDCCHs that transmit RAR messages based on the packet size or CE level of the PRACH signal to the BS. which answers the RAR message. That is, a BS transmits a signal indicating that PRACH signals of a first packet size or first CE level or less will be answered (by the BS) with RAR messages in a first common search space MPDCCH and PRACH signals of a packet size greater than the size of the first packet or CE level greater than the first CE level will be responded to with RAR messages on a second MPDCCH common search space. The information may be transmitted, for example, in a system information block (SIB). If a BS is configured with more than two MPDCCH common search spaces for more than two packet sizes or CE levels, the BS may transmit information regarding all MPDCCH common search spaces, packet size thresholds, and packet size thresholds. EC level.

In accordance with aspects of the present disclosure, an MTC UE may be configured with a first MPDCCH common search space in a first narrowband region for MPDCCHs carrying RAR messages (eg, as in operation 800 in Figure 8 above). . The MTC UE may transmit a PRACH signal to a Bs in a second narrowband region. The UE may receive an MPDCCH carrying a RAR message from the BS in the first common search space MPDCCH. The UE may receive information about the first common search space MPDCCH for MPDCCHs carrying RAR messages in a system information block (SIB).

In accordance with some aspects of the present disclosure, a UE may receive an MPDCCH carrying a paging signal multiplexed (eg, as in technique 910 in Figure 9 above) with the MPDCCH carrying the RAR message in the first space. common search MPDCCH in at least one subframe.

A UE may receive an MDPCCH carrying a paging signal in the first MPDCCH common paging space in another subframe (eg, as in technique 920 in Figure 9 above). In accordance with aspects of the present disclosure, the MPDCCH carrying the RAR message may be grouped into non-continuous subframes and the MPDCCH carrying the paging signal may be grouped into non-continuous subframes (eg, as in technique 930 in Figure 9 previous).

An MTC UE may be configured with a first MPDCCH common search space for MPDCCHs carrying paging signals and a second MPDCCH common search space for MPDCCHs carrying RAR messages (eg, as in technique 1010 in Figure 10 above). The first and second MPDCCH common search spaces may each be within different narrowband regions of a wider system bandwidth.

An MTC UE may identify a third common search space MPDCCH for MPDCCHs carrying RAR messages (eg, as in technique 1020 in Figure 10 above). The UE may determine to monitor the second common search space MPDCCH for MPDCCHs carrying RAR messages or the third common search space MPDCCH for MPDCCHs carrying RAR messages based on a coverage improvement (CE) level of the UE. The UE may receive information about the second common search space MPDCCH for MPDCCHs carrying RAR messages and the corresponding CE level in a system information block (SIB). The UE may also receive information regarding the third MPDCCH common search space for MPDCCHs carrying RAR messages and the corresponding CE level in a SIB.

An MTC UE may identify a third common search space MPDCCH for MPDCCHs carrying RAR messages (eg, as in technique 1030 in Figure 10 above). The UE may determine to monitor the second common search space MPDCCH for MPDCCHs carrying RAR messages or the third common search space MPDCCH for MPDCCHs carrying RAR messages based on the narrowband or subband region used to transmit the PRACH signal. The UE may receive information about the second MPDCCH common search space for MPDCCHs carrying RAR messages and the corresponding PRACH subband in a system information block (SIB). The UE may also receive information regarding the third common search space MPDCCH for MPDCCHs carrying RAR messages and the corresponding PRACH subband in a SIB.

A BS can determine whether to multiplex MPDCCHs carrying paging signals and MPDCCHs carrying RAR messages in the same subframes in a common MPDCCH paging space as illustrated in technique 910 shown in Figure 9, or to transmit MPDCCHs carrying paging signals and MPDCCHs carrying RAR messages using other techniques. A BS that supports only low CE levels or packet sizes may determine to multiplex the MPDCCHs carrying paging signals and the MPDCCHs carrying RAR messages. A BS that supports higher Ce levels (eg, 15 dB) or packet sizes (eg, 10 subframes) may determine time division multiplexing MPDCCHs carrying paging signals and MPDCCHs carrying RAR messages as illustrated in technique 920 shown in Figure 9. Alternatively, the BS supporting the higher CE levels or packet sizes may determine to transmit MPDCCHs carrying paging signals on a first common search space MPDCCH and transmit MPDCCHs carrying RAR messages into one or more MPDCCH common search spaces as in techniques 1020 and 1030 shown in Figure 10.

In accordance with aspects of the present disclosure, a BS may transmit an indication of a RAR response window for each of a plurality of CE levels. A RAR response window is a period of time that a UE must monitor for RAR messages after transmitting a PRACH signal before determining that the UE should transmit a PRACH signal. A BS may transmit an indication of a number of RAR offset subframes or RAR response window for each of the plurality of CE levels. A RAR offset is a period of time that a Ue must wait after finishing the PRACH transmission before starting to monitor RAR messages for the RAR response window. An MTC UE may have a longer RAR offset than a standard UE due to, for example, retune time or half-duplex capability.

A BS may transmit an indication of a set of MPDCCH start point subframes for each of the plurality of CE levels. The set of MPDCCH start point subframes are the subframes at which the BS can start transmitting an MPDCCH (eg, the first subframe of a packet of subframes). A BS may transmit an indication of a packet size for each of the plurality of CE levels.

In accordance with aspects of the present disclosure, a BS may determine a paging radio frequency, paging time, and packet size for MPDCCHs carrying paging signals, based on a maximum supported Ce level for the BS.

In accordance with aspects of the present disclosure, a BS may transmit a system information (SI) change or an earthquake and tsunami warning system (ETWS) signal on a broadcast channel of the highest system bandwidth. The BS may transmit the same SI or ETWS changeover signal in dedicated signaling to one or more MTC UEs in narrowband regions, because UEs in connected mode (i.e. not in idle mode) may not monitor broadcast channels of the widest bandwidth of the system.

In accordance with aspects of the present disclosure, an MTC UE that is in connected mode may periodically tune out of the narrowband region assigned to the MTC UE and tune into the wider bandwidth broadcast region of the system. A BS supporting the MTC UE may determine the time periods that the MTC UE tunes outside the narrowband region assigned to the MTC UE and refrain from transmitting any dedicated channels to the UE. The BS may transmit a System Information (SI) or Earthquake and Tsunami Warning System (ETWS) change signal to the MTC UE on a transmission channel of the wider system bandwidth in periods of time than the MTC The UE has tuned outside the narrowband region assigned to the MTC UE to improve the probability that the MTC UE will receive the SI and/or ETWS switching signal.

In accordance with aspects of the present disclosure, a BS serving a UE (eg, an MTC UE) with the UE in connected mode (eg, DRX connected mode) may cause the UE to enter a disconnected mode. The BS can cause the UE to switch to a disconnected mode, for example, by sending an explicit command to disconnect or by refraining from responding to transmissions from the UE, which can cause the UE to declare a radio link failure (RLF). and disconnect from the BS. The BS can cause the UE to switch to a mode disconnected so that the UE can monitor the paging channels to receive notifications of a change of an SI and/or ETWS signal.

Figure 11 illustrates example operation 1100 for wireless communications that may be performed by a BS (eg, eNodeB 110a in Figure 1), in accordance with aspects of the present disclosure. Operation 1100 may be performed by a BS to encrypt transmissions for and otherwise support MTC UEs.

Operation 1100 begins at block 1102, where the BS determines a coverage enhancement (CE) level of a UE. Operation 1100 continues at block 1104, where the BS initializes an encryption sequence to transmit a signal to the UE based on the CE level. At block 1106, the BS encrypts the signal to the UE with the encryption sequence. At block 1108, operation 1100 continues with the BS transmitting the encrypted signal to the UE.

Figure 12 illustrates example operation 1200 for wireless communications that a UE (eg, UE 120a in Figure 1) may perform, in accordance with aspects of the present disclosure. Operation 1200 may be performed by an MTC UE to decrypt, for example, an MPDCCH. Operation 1200 can be considered complementary to operation 1100 in Figure 11 described above.

Operation 1200 begins at block 1202, where the UE initializes an encryption sequence based on a coverage enhancement (CE) level of the UE. Operation 1200 continues at block 1204, where the UE receives a signal encrypted with the encryption sequence. At block 1206, the UE decrypts the signal with the encryption sequence.

Figure 13 illustrates example operation 1300 for wireless communications that may be performed by a BS (eg, eNodeB 110a in Figure 1), in accordance with aspects of the present disclosure. Operation 1300 may be performed by a BS to encrypt transmissions for and otherwise support MTC UEs.

Operation 1300 begins at block 1302, where the BS encrypts a first demodulation reference signal (DM-RS) to a first UE with an initialized encryption sequence with an encryption sequence initialization. Operation 1300 continues at block 1304, where the BS encrypts a second DM-RS to a second UE with a second encryption sequence initialized with the encryption sequence initialization. At block 1306, the BS transmits the first scrambled DM-RS to the first UE and the second scrambled DM-RS to the second UE in a same search space.

Figure 14 illustrates example operation 1400 for wireless communications that a UE (eg, UE 120a in Figure 1) may perform, in accordance with aspects of the present disclosure. Operation 1400 may be performed by an MTC UE to decrypt, for example, an MPDCCH. Operation 1400 can be considered complementary to operation 1300 in Figure 13 described above.

Operation 1400 begins at block 1402, where the UE receives a first demodulation reference signal (DM-RS) encoded with a cipher sequence initialized with a cipher sequence initialization. Operation 1400 continues at block 1404, where the UE receives a signal encrypted with the first encryption sequence in a search space, wherein at least one second DM-RS encrypted with a second encryption sequence initialized with the initialization of the encryption sequence is transmitted in the search space. At block 1406, the UE decrypts the signal with the encryption sequence.

In accordance with aspects of the present disclosure, a BS supporting MTC UEs may use a fixed encryption ID when encrypting MPDCCHs (eg, as in operation 1100 in Figure 11 above) or reference signals associated with MPDCCHs (eg , DM-RS) to be transmitted on a common search space MPDCCH. The encryption ID is set such that all UEs receiving the MPDCCH can decrypt the MPDCCH. The fixed encoding ID may be carried in a SIB (eg SIB1).

The encryption of MPDCCHs may be similar to the encryption of EPDCCH as described in 3GPP TS 36.213 “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures” and 3GPP TS 36.211 “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation”, which are publicly available. The variable Yp,k used to determine MPDCCH decoding candidates is initialized with either the Paging Radio Network Temporary Identifier (P-RNTI) or the Random Access Radio Network Temporary Identifier (RA-RNTI), depending on whether the MPDCCH transmits a paging signal or a RAR message. In some cases, MPDCCH decoding candidates may be determined by the maximum coverage enhancement level supported by a BS, which may be signaled in a SIB1 transmitted by the BS. As stated above, the encryption ID nMPDCCHSCID is set for all UEs served by a cell. In order to improve encryption between EPDCCH and MPDCCH, the encryption ID can be set to 3, which differs from the encryption ID for EPDCCH n ^EPDCCHID,m which is normally set to 2. The encryption initialization for MPDCCH is then :

Cinit = (LJ?s/ 2 j 1) • (2?7epdcch ID,i 1) • 216 ^ pdcch scm

The encryption ID may depend on the CE levels of the signaling UEs. For example, a BS may use n ^MPDCCHSCID = 2 as the encryption ID when signaling UEs that are operating with no CE or with small CE (for example, CE level of 0 dB) and the BS may use 3 as the encryption ID when signaling UEs that are operating with a higher CE (eg, CE level of 10 dB).

An encryption sequence initialization may be cell-specific, in accordance with aspects of the present disclosure. That is, one BS may use one encryption sequence initialization to encrypt all MPDCCHs to UEs in a cell, while other BSs may use other encryption sequence initializations to encrypt MPDCCHs to UEs served in other cells.

In accordance with aspects of the present disclosure, the encryption sequence may comprise a demodulation reference signal (DM-RS).

In accordance with aspects of the present disclosure, a BS may transmit an encrypted signal to an Enhanced Machine Type Communications (eMTC) UE multiplexed with an encrypted signal to a non-eMTC UE in a same resource block.

In accordance with aspects of the present disclosure, a UE may receive an encrypted signal from a BS, initialize an encryption sequence based on a CE level of the UE, and decrypt the encrypted signal with the encryption sequence (eg, as in operation 1200 in Figure 12 above). The encrypted stream may comprise a DM-RS. Another signal can be multiplexed with the encrypted signal in the same resource block.

In accordance with aspects of the present disclosure, a UE may monitor MPDCCHs of different repetition levels for reception of a paging channel. For example, the eNB may transmit paging-related MPDCCHs with repetition levels R selected from the set {1, 4, 32, 256}. The great variability in the number of repetitions of MPDCCHs allows an eNB to adapt to UEs with widely varying coverage levels. In some cases, a UE with good coverage may need to monitor only the lower repetition levels (eg, R e {1,4}), and if the eNB transmits with a higher repetition level, the UE may decode early. For example, if eNB transmits with R=32, the UE may be able to decode earlier with a smaller number of repetitions (eg, R=8). That is, while the eNB transmits the MPDCCH 32 times (repetition level 32) in the example, the UE can correctly decode the MPDCCH after the 8th repetition, and the Ue can deactivate a receiver after the 8th repetition, thus conserving power. It may be important for a UE to correctly assess the repetition levels to monitor in order to reduce the power consumption of the UE while maintaining good communications reliability.

In accordance with aspects of the present disclosure, a BS (for example, the BS mentioned in Figure 7 and/or Figure 15) can determine a set of repetitions for transmitting a downlink channel, based at least in part on a coverage enhancement (CE) level of a UE, determining a power boost value for the downlink channel, transmitting an indication of the power boost value for the downlink channel, and transmitting the downlink channel based on rep set and power increase value. The BS may determine different power increase values for at least one repetition in the set of repetitions. That is, a BS can determine how much to boost a channel to a UE and how many repetitions to use based on the CE level information of the UE, and then the BS can transmit the channel (for example, an MPDCCH) to the UE for the number number of reps, with each rep powering one of the set amounts.

In some cases, the evaluation of the repetition levels to be monitored by a UE can be made based on the quality of the measured received signal. For example, a UE may measure RSRP, downlink RSRQ, and/or signal-to-noise ratio (SNR) based on a cell-specific reference signal, and the UE may decide the repetition level to monitor paging. based at least in part on this measurement. In accordance with aspects of the present disclosure, a UE may determine a repetition level necessary to decode MPDCCHs to a certain reliability (for example, a 1% missed detection rate) and select to monitor a repetition level lower than set of repetition levels that meets that requirement. For example, a UE may have a reliability requirement to receive MPDCCHs with a 1% missed detection rate, determine that repetition levels of 32 and 256 meet that requirement, and select to monitor MPDCCHs at a repetition level of 32. because it is less than the repeat level of 256.

In some cases, the MPDCCHs for paging may be boosted to reduce the decoding time for a UE in deep coverage. When increasing the power of the MPDCCHs for paging, the UE may take into account a value of increasing the power of the MPDCCHs when evaluating a repetition level or levels to monitor. The UE can determine a repetition level needed to decode the MPDCCHs up to a certain reliability (for example, 1% failure detection rate) and choose the lowest repetition level that meets that requirement taking into account the boost value of power of the MPDCCHs. For example, if a UE determines that an SNR value for signals from an eNB is -5dB, and the power boost value for MPDCCHs for paging is 3dB, then the UE may determine to monitor MPDCCHs using a repetition level based on a effective SNR value of -5 3 = -2dB. The power boost value used by an eNB may be broadcast by the eNB in system information, communicated to a UE in a unicast manner (eg via an RRC message), or carried by higher layer signalling. Also, different levels The repetition levels can have different power boost values, whereby the eNB can determine and transmit indications of a set of power boost values corresponding to each (or a subset) of the repetition levels, and a UE can determine a subset of the repetition levels or a maximum repetition level based at least in part on a measured received signal quality and the indicated set of power boost values. As before, the eNB may transmit the indications of the set of power boost values, transmit the indications in a unicast manner, or transport the indications via higher layer signaling.

In accordance with aspects of the present disclosure, a UE (eg, the UE mentioned in Figure 8) may receive a paging signal in a second paging space in a third narrowband region. That is, a UE may transmit a PRACH signal in a first narrowband region, receive a RAR message responding to the PRACH in a second narrowband region, and receive a paging signal in another paging space in the third narrowband region. Narrow band.

In accordance with aspects of the present disclosure, a UE (for example, the UE mentioned in Figure 8 and/or Figure 15) can determine a first set of repetitions for receiving a downlink channel, based at least in part at a maximum coverage enhancement (CE) level supported by the BS, determining the quality of the received signal, determining a second set of repetitions for receiving the downlink channel based at least in part on the first set of repetitions, and the quality of the received signal, and receiving the downlink channel based on the second set of repetitions. The UE may further receive an indication of a power boost value for the downlink channel and determine the second set of repetitions for receiving the downlink channel based further on the power boost value indication. The indication of the power increase value for the downlink channel may indicate different power increase values for different repetitions in the first set of repetitions. Additionally or alternatively, the downlink channel may be a control channel associated with a paging channel. Also additionally or alternatively, the UE may enter a discontinuous receive (DRX) mode if the UE does not receive the downlink channel.

Figure 15 illustrates an example transmission timeline 1502 of a BS (for example, eNB 110a shown in Figure 1) and an example transmission timeline 1510 of a UE (for example, UE 120a shown in Figure 1). shown in Figure 1) operating in accordance with aspects of the present disclosure. The UE may be an MTC UE, as described above. In example timelines 1502 and 1510, each block represents a subframe. During time 1504, the BS transmits an MPDCCH at a repetition level of 32. The MPDCCH may be, for example, scheduling a PDSCH addressed to an MTC UE, such as UE 120a shown in Figure 1. increase the power of the MPDCCH, as described above. In the example timelines, the MPDCCH is boosted, and the MTC UE successfully receives and decodes the MPDCCH in eight subframes during the time shown at 1512. The MTC UE has information about the repetition level used by the BS, and turns off a receiver of the MTC UE for the remaining portion of time 1514, as illustrated by the unfilled boxes. During time 1506, the BS transmits the scheduled Pd SCH on the MPDCCH to the MTC UE. During time 1516, the UE activates the UE's receiver and receives and decodes the PDSCH. As illustrated, the MTC UE may keep the receiver active for the 32 repetition level subframes, if necessary, to successfully receive the PDSCH.

As used herein, a phrase referring to "at least one of" a list of elements refers to any combination of those elements, including the individual members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, ab, ac, bc, and abc, as well as any combinations with multiples of the same element (for example, aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc or any other order of a, b, and c).

The steps of a method or algorithm described in connection with the disclosure herein may be performed directly in hardware, in a software module executed by a processor, or in a combination of the two. Examples of processors include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, closed logic, discrete hardware circuits, and other suitable hardware. configured to perform the various functions described throughout this disclosure. Software shall be broadly construed to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects , executables, threads, procedures, functions, etc., whether called software, firmware, middleware, microcode, hardware description language, or otherwise. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, PCM (phase change memory), registers, hard disk, removable disk, CD-ROM, or any other form of media. storage known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from and/or write information to the storage medium. Alternatively, the storage medium may be an integral part of the processor. The processor and storage medium may reside in an ASIC. The ASIC may reside in a user terminal. Alternatively, the processor and storage medium may reside as discrete components in a user terminal. In general, when there are operations that are illustrated in the Figures, those operations may have corresponding middle plus function components with similar numbering.

In one or more exemplary designs, the described functions may be implemented in hardware, software, or combinations thereof. If implemented in software, the functions may be stored or transmitted as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media, including any media that facilitates the transfer of a computer program from one location to another. A storage medium can be any available medium that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media may comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can used to carry or store the desired program code media in the form of instructions or data structures and which can be accessed by a general purpose or special purpose computer, or a general purpose or special purpose processor. Also, any connection is properly called a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disc and magnetic disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc where discs generally reproduce data magnetically, at the time discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer readable media.

The foregoing description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications of the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Therefore, the disclosure is not intended to be limited to the examples and designs described herein, but is to be accorded the widest scope in accordance with the appended claims.

Claims (15)

1. A method for wireless communications performed by a base station, BS, comprising: receive (702) a physical random access channel, PRACH, signal from a first user equipment, UE, in a first narrowband region comprising one to six resource blocks, RBs, within a wider bandwidth Uplink System, UL; determining a first search space (1032, 1034) in which a random access response, RAR, message is transmitted based at least in part on the coverage enhancement level, CE, of the UE; and transmit (704), in response to the PRACH signal, the RAR message in the first search space, which is in a second narrowband region comprising one to six RBs within a wider bandwidth of the search system downlink, DL, in at least a first subframe. 2. The method of claim 1, further comprising: transmit a paging signal in a second paging space in a third narrowband region comprising one to six RBs within the wider bandwidth of the DL system 3. The method of claim 1, further comprising: identify a third search space in a fourth narrowband region comprising one to six RBs within the wider bandwidth of the DL system to transmit messages rA ra to a second UE with a coverage enhancement level, CE, different from first EU; transmitting information regarding the first search space and a first CE level for the first search space in a system information block, SIB; and transmitting information regarding the third search space and a second CE level for the third search space in at least one of the SIBs or another SIB. 4. A method for wireless communications performed by a user equipment, UE, comprising: transmitting (802) a physical random access channel signal, PRACH, to a base station, BS, in a first narrowband region comprising from one to six resource blocks, RBs, within a wider uplink system bandwidth, UL; determining a first search space (1032, 1034) for monitoring a random access response, RAR, message based at least in part on a coverage improvement level, CE, of the UE; and receive (804), in response to the PRACH signal, the RAR message in the first search space, which is in a second narrowband region comprising one to six RBs within a wider bandwidth of the search system downlink, DL, in at least a first subframe. 5. The method of claim 4, further comprising: receiving a paging signal in a second paging space in a third narrowband region comprising one to six RBs within the wider bandwidth of the DL system. 6. The method of claim 5, further comprising: determining a first set of repetitions for receiving a downlink channel, based at least in part on a maximum coverage enhancement level supported by the BS; determine the quality of a received signal; determining a second set of repetitions to receive the downlink channel based, at least in part, on the first set of repetitions and the quality of the received signal; and receive the downlink channel based on the second set of repetitions. 7. The method of claim 6, further comprising: receiving an indication of a power increase value for the downlink channel; and determining the second set of repetitions to receive the downlink channel further based on the power increase value indication. The method of claim 6, further comprising entering a discontinuous receive mode if the downlink channel is not received. 9. The method of claim 4, further comprising: identifying a third search space in a fourth narrowband region comprising one to six RBs within the wider bandwidth of the DL system to receive RAR messages; receiving information about the first search space and a first CE level for the first search space in a system information block, SIB; and receive information about the third search space and a second level of CE for the third search space in at least one of the SIBs or another SIB. 10. The method of claim 4, further comprising: determining a RAR response window, a set of machine communications physical downlink control channel start point subframes, a number of RAR offset subframes, and a packet size for each of a plurality of levels of coverage improvement, CE. 11. The method of claim 4, further comprising: determining a paging radio frequency, a paging time, a paging packet size, and a set of monitoring candidates based on at least one maximum coverage enhancement level, CE, supported by the BS. 12. An apparatus for wireless communications, comprising means for carrying out a method according to any of claims 1 to 3. 13. An apparatus for wireless communications, comprising means for carrying out a method according to any of claims 4 to 11. 14. A computer-readable medium for wireless communication, comprising instructions which, when executed by a computer, cause the computer to carry out the method of any one of claims 1 to 3. 15. A computer-readable medium for wireless communication, comprising instructions which, when executed by a computer, cause the computer to carry out the method of any one of claims 4 to 11.